The field of the present disclosure relates generally to optical code readers and, in particular, to systems and methods for adjusting an illumination mode of an optical code reader.
An optical code, such as a barcode, is essentially a machine-readable representation of information in a visual format. Some optical codes use a dark ink on a white substrate to create high and low reflectance upon scanning or reading of the optical code. (For the purposes of the present description, the terms scan and read, may be used interchangeably to connote acquiring data associated with an optical code. Likewise, scanner and optical code reader may be used interchangeably to connote devices used to acquire data associated with an optical code.) Based on the symbology being used (e.g., UPC, Code 39, Code 128, and PDF417), an optical code may comprise data characters (or codewords in the case of, e.g., PDF417) and/or overhead characters represented by a particular sequence of bars and spaces that may have varying widths.
Optical codes have widespread applications. For example, optical codes can be used to identify a class of objects (e.g., merchandise) or unique items (e.g., patents). As a result, optical codes are found on a wide variety of objects, such as retail goods, company assets, and documents. The optical codes are placed on items and read as the items arrive or as they are sold to help track production at manufacturing facilities or inventory at stores.
In addition, optical codes may appear on a display of a portable electronic device, such as a mobile telephone, personal digital assistant, tablet computer, laptop computer, or other device having an electronic display. For example, a customer, such as a shopper, airline passenger, or person attending a sporting event or theater event, may cause an optical code to be displayed on their portable electronic device so that an employee (e.g., merchant-employee) can read the optical code via an optical code reader to allow the customer to redeem a coupon or to verify that the customer has purchased a ticket for the event.
Optical code readers are a type of data reader used to capture optical codes or other symbols or information appearing on various surfaces in order to read the information encoded in the optical code or symbol. One commonly used optical code reader is an imaging based reader. Imaging based readers typically include solid state image circuitry, such as charge coupled devices (CCDs) or complementary metal-oxide semiconductor (CMOS) devices, and may be implemented using a one-dimensional or two-dimensional imaging array of photosensors (or pixels) to capture an image of the optical code. One-dimensional CCD readers capture a linear cross section of the optical code, producing an analog waveform whose amplitude represents the relative darkness and lightness of the optical code. Two-dimensional CCD or CMOS readers may capture an entire two-dimensional image.
Although some optical code readers rely on ambient light when capturing an image of an optical code, many optical code readers utilize an illumination source to illuminate the optical code in an attempt to improve the image data quality generated by the imaging device. The illumination source may facilitate low noise image capture and may also delineate the field of view of the optical code reader to help the user aim the optical code reader or position the object bearing the optical code. In some situations, however, the illumination intensity provided by the illumination source may be substantial and counterproductive.